DESCRIPTION (Adapted from abstract): The proposal is for continued development of the HKL suite of programs Denzo/Scalepack/XDisplayF for data reduction and scaling of x-ray diffraction data. New areas for development fall in three categories. Advancing the solution of the phase problem will be addressed by optimization of single-wavelength anomalous dispersion from sulfur, use of nonisomorphism as a source of phase information, and implementation of a method for calibration for CCD detectors, a generalized absorption correction, and a new interface for phasing tree analysis. Continued development of methods for improving data quality will be aimed at obtaining useful diffraction data from less than optimal crystals. The third area for development will be in standardizing optimal data collection strategies and data archiving.